Coke ovens with a high output require that the material be subjected to a temperature of 1200.degree. to 1400.degree. C. for about 16 to 20 hours. A further increase in the output of the coking ovens is greatly to be desired; however, in the present state of the art such an increase in output can be achieved only by raising the temperature of the system. One difficulty arises from the fact that in raising the heating flue temperature beyond 1400.degree. C. the loss in heat through radiation becomes excessive. Moreover, the life of the heating flue wall which at the present time is usually constructed of chamotte or silica firebrick is greatly reduced through the increased temperature, thus introducing an increase in cost.